We examined the discriminant validity of the Inventory to Diagnose Depression, lifetime version (IDDL), that is, a self-report instrument designed to diagnose a lifetime history of major depressive disorder. Remitted patients with major depression (MD), remitted patients with anxiety disorders (ADs) and controls completed the IDDL. The IDDL results were then compared in the three contrasts: MD vs. ADs + controls, MD vs. ADs, and MD vs. controls. The agreement between the IDDL and clinical diagnoses was high in each of the three contrasts, and the IDDL total score in the MD group was the highest among the three groups and distinguished from the ADs group or controls. However, the IDDL occasionally diagnosed subjects with a lifetime history of ADs as having a lifetime history of MD.